This invention relates, generally, to an improved heat exchange assembly, and particularly to a heat exchange assembly having a novel arrangement of headers suitable for use with a novel header construction.
A myriad of heat exchange devices are known to supply heated water and steam for domestic, commercial, and industrial purposes. Factors which determine the suitability and costs of a heat exchange device for any given purpose include the device's operating or performance characteristics as well as the method and materials required for the device's manufacture, maintenance, and repair. For any given purpose, most heat exchange devices have technical disadvantages relating to at least one of their operation, manufacture, maintenance, or repair, while those devices which may be technically suitable are generally prohibitably expensive for the intended use.
Performance characteristics of a heat exchange device adapted to transfer heat to a fluid contained therein include characteristics such as start-up time, energy efficiency and heat output, thereby determining the quality and quantity of heated fluid which may be produced. Operations strictly dependent on hot water supply, such as car washing systems, may have special performance requirements not usually met by heat exchange devices. For example, car washing systems often operate intermittently requiring large volumetric flow rates for short time intervals and favouring fluid heating devices with small start-up times. However, most fluid heating devices designed for car washing systems either have excessively lengthy start-up times suitable only for continuous operation, or have adequate start-up times but low energy efficiencies.
Most known heat exchange devices suffer from the disadvantage that they are manufactured by sophisticated methods developed for use with specialized materials. These methods are generally incompatible with the use of more conventional materials such as standard commercial pipe and tubing. Repair to such devices must be carried out by skilled repairmen using expensive and frequently unavailable replacement parts. Few heat exchange devices exist in which repair may be easily affected by nominally skilled persons using readily available tools and materials. Notwithstanding these difficulties of repair, designs of heat exchange devices seldom facilitate or even permit effective maintenance which could eliminate many device failures and prolong device life as well as maintain device energy efficiencies.
The disadvantages of known heat exchange devices may be further illustrated by reference to coil water heater, typical of many conventional fluid heating devices which comprise a heat exchange assembly, in this case a coil, which along with a fuel burner may be located within a furnace enclosure. The coil, formed as a continuous single tube, is placed in the furnace enclosure so that water passing through the coil is heated by heat transferred through the walls of the coil from hot air produced in the furnace enclosure by the combustion of gas or oil in the burner. Such coil water heaters have the disadvantage that the coil is expensive to manufacture and, in the event of failure, must be replaced by a similarly expensive coil. In addition, to design coil water heaters with different performance characteristics, coils of different diameters and lengths are required. Increases in the dimensions of the coil greatly increase the relative cost of coil manufacture. As a further disadvantage, in maintenance, the curvature of the coil makes it difficult to insert cleaning snakes or reamers into the coil to effect proper cleaning and scale removal.